The present invention relates to a cigar lighter for use in vehicles or the like.
German publication DE-P.S. No. 1802931 discloses an electrical lighter having a plug body formed of an outer sleeve shell removably insertable in a cylindrical socket which is fixedly secured in the dashboard of the vehicle. Slidably located in the outer sleeve is an inner sleeve shell and a heating element comprising a spiral resistance coil, located in a cup, mounted on one end of a central post, the other end of the post being attached to an insulating knob fixed to the inner sleeve. The post is centered within the outer sleeve shell by a fixed bracket through which the center post freely passes. A helical compression spring located between the fixed bracket and the knob biases the inner sleeve normally outward from the outer sleeve. In use, the outer sleeve is insertable into the socket, which is provided with a central hub constituting a first electrical terminal, and a plurality of bimetal latch spring fingers arranged to grasp the heating coil cup about its periphery constituting the second electrical terminal. After insertion of the outer sleeve, into the socket, the knob is depressed pushing the heating element to engagement with the bimetal latch fingers and the central hub, completing the circuit through the heating coil. When the coil heats the bimetal latch fingers, they become hot, distend, and release the cup allowing the entire plug body to pop outwardly. After release has taken place, the heating element together with the knob is automatically moved outward relative to the outer sleeve under the effect of the helical spring so that the knob protrudes so far out of the socket, beyond the dashboard, that it can be gripped and the entire plug body can be pulled out of the socket for use.
In such a cigar lighter, current is switched on when the knob is pressed in and the connection to the vehicle battery is produced. At the same time, an induction of the operational state is made, since the knob remains in its pressed-in position until the coil and cup is released by the bimetal latches operating as a control device after attainment of the desired heating temperature. In that case, the knob and entire heating element jumps under the effect of the spiral spring so far out of the socket that an indication of the readiness for use of the heated cigar lighter is provided.
It is a disadvantage in such a cigar lighter that a plurality of parts is requied, which in operation are movable one relative to the other, so that faults can eventually result due to wear. In particular, the possibility exists that the current supply contacts with socket and coil can become welded together preventing the release of the bimetal latches and the interruption of the contact to the vehicle battery, so that the helical spring is no longer in a position of breaking the contact and poping the lighter. Overheating of the coil can thus set in, leading to destruction of the coil as well as to cause heat damage to those parts arranged in proximity to the lighter on the dashboard. Beyond that, it is possible that the knob, after release by the bimetal latches is instantly thrown back into the removal position under the influence of the spiral spring so that the resultant high acceleration forces are produced on the heated coil, appreciably reducing its life. Although it is known to damp these shocks on the coil by elastic buffers, additional mechanical parts are however required for this; moreover such parts cannot assure the complete elimination of shock on the coil.
The problem forming the basis of the present invention thus consists in further developing a cigar lighter of the initially named kind in the sense that, to increase the reliability of use, mechanically moved parts are largely avoided and shock to the coil is excluded in operation.